an Al-enriched parent material and hydrous supergene or hypogene conditions at a low to moderate T (< 370°C) and P regime (below low-grade regional metamorphic conditions) and pH < 7.
HGD
DILL, H.G. (2016) Kaolin: soil, rock and ore From the mineral to the magmatic, sedimentary, and metamorphic environments.- Earth Sciences Reviews 161: 16-129.